EFFECT OF LOCAL TISSUE COOLING ON MICROVASCULAR SMOOTH-MUSCLE AND POSTJUNCTIONAL ALPHA-2-ADRENOCEPTORS
EFFECT OF LOCAL TISSUE COOLING ON MICROVASCULAR SMOOTH-MUSCLE AND POSTJUNCTIONAL ALPHA-2-ADRENOCEPTORS
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DOI：
10.1152/ajpheart.1988.255.1.h121
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发表时间：
1988-07-01
影响因子：
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通讯作者：
FABER, JE
中科院分区：
文献类型：
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作者：
FABER, JE
在大鼠提睾肌上研究了局部组织冷却对微血管平滑肌收缩行为和对肾上腺素能收缩敏感性的影响。活体显微镜用于测量第一和第二级小动脉的直径（对照直径=101 ± 0.5mm）。7 μ m）和小静脉（直径=142 ± 0.7 μ m）。9 μ m）和三级末端小动脉（直径=19 ± 10 μ m）。4 μ m）。向提睾肌浴中加入去甲肾上腺素（NE），使在34 ℃下获得的对照直径减少20-35%。C浴温度（原位提睾器温度）。在NE存在下，将浴冷却至26 ℃。C引起大动脉和小静脉的额外收缩。末端小动脉表现出更明显的冷却诱导收缩。自发性血管舒缩，仅在这种血管类型中明显，被取消冷却。冷却引起的收缩和血管舒缩的抑制在复温至34 ℃时是可逆的。C.用育亨宾（1- 5x）阻断连接后α 2-肾上腺素受体。10-7 M）完全消除了冷却诱导的收缩，α 1-和α 2-肾上腺素受体拮抗剂酚妥拉明（10-6 M）也是如此;用哌唑嗪（10-8 M）阻断α 1-肾上腺素受体对反应没有影响。在用育亨宾或酚妥拉明抑制去甲肾上腺素能收缩后，局部冷却使终末小动脉扩张;然而，扩张是短暂的。这些数据表明，适度的组织冷却对微血管平滑肌张力有直接的，尽管是短暂的，但却是可逆的影响。然而，在存在肾上腺素能收缩的情况下，局部组织冷却的抑制作用被α 2介导的而非α 1介导的血管收缩的选择性增加所克服。
The effect of local tissue cooling on microvascular smooth muscle contractile behavior and sensitivity to adrenergic constriction was examined in rat cremaster skeletal muscle. Intravital microscopy was used to measure the diameter of first- and second-order arterioles (control diam=101 .+-. 7 .mu.m) and venules (diam=142 .+-. 9 .mu.m), and third-order terminal arterioles (diam=19 .+-. 4 .mu.m). Norepinephrine (NE) was added to the cremaster bath to produce a 20-35% reduction in control diameter obtained at 34.degree. C bath temperature (in situ cremaster temperature). In the presence of NE, cooling the bath to 26.degree. C caused additional constriction of large arterioles and venules. Terminal arterioles exhibited a more pronounced cooling-induced constriction. Spontaneous vasomotion, evident only in this vessel type, was abolished by cooling. Cooling-induced constriction and inhibition of vasomotion were readily reversible with rewarming to 34.degree. C. Blockade of postjunctional .alpha.2-adrenoceptors with yohimbine (1-5 .times. 10-7 M) completely abolished cooling-induced constriction, as did the .alpha.1- and .alpha.2-adrenoceptor antagonist phentolamine (10-6 M); blockade of .alpha.1-adrenoceptors with prazosin (10-8 M) had no effect on the response. After inhibition of the noradrenergic constriction with yohimbine or phentolamine, local cooling dilated terminal arterioles; however, the dilation was transient. These data suggest that modest tissue cooling has a direct, although transient, depressant effect on microvascular smooth muscle tone. However, in the presence of adrenergic constriction, the inhibitory effect of local tissue cooling is overcome by a selective increase in .alpha.2- but not .alpha.1-mediated vasoconstriction.